PowerBuilder Interview Question and Answers

105. What are Non-Visual User Objects?
  Non-visual user object is an object that encapsulates attributes and functions but is not visible to the user. NVO is a collection of business user functions. They can be Custom Class and Standard Class. NVOs are useful because they allow you to encapsulate application operations into objects making them easier to develop, manage and maintain and also to encapsulate all security management for an application into a single object.
 
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106. Explain the purpose of a non-visual user objects?
  The purpose of non-visual user objects is to define business rules and other processing (which are checked in different windows in your application) that act as a unit. We implement them in PowerBuilder using Class User Objects.
 
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107. What are facilities of the User Objects?
  We define a component once, then reuse it many times as we need without any additional work.
 
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108. What does OpenUserObject() do?
  OpenUserObject() adds a user object to the specified window and makes all its properties and controls available to scripts. windowname.OpenUserObject ( userobjectvar, userobjecttype {, x, y } ) This function is used when you want dynamically, at runtime place some user objects on a window. This function displays this user object, makes all its attributes available to scripts. You must open a user object before you can access the attributes of the user object. If you access the user object’s attributes before you open it, it will cause an execution error.
 
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109. How can you dynamically place an User Object on the window?
  By using functions : OpenUserObject( ), OpenUserObjectWithParm( )
 
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110. What Events does the Custom Class have?
  Constructor and Destructor
 
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111. What events are available to a standard class User Object?
  Constructor and Destructor.
 
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112. How is a custom visual UserObject different from a standard UserObject?
  A custom visual user object is an object that has several controls that work as a unit. A standard visual user object inherits its definition from a standard control. We modify the definition to make the control specific to our applications.
 
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